Secondary hemophagocytic lymphohistiocytosis triggered by Klebsiella pneumoniae: A case report of recovery without immunosuppression

Abstract

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome that may mimic severe sepsis, resulting in delayed diagnosis. Bacterial infection-associated HLH is uncommon, particularly with Klebsiella pneumoniae . We report a case of a 38-year-old male presenting with community-acquired pneumonia, persistent fever, pancytopenia, hepatosplenomegaly, and marked hyperferritinemia. Bronchoalveolar lavage culture isolated K. pneumoniae , whereas bone marrow aspiration demonstrated hemophagocytosis. The patient fulfilled five HLH-2004 diagnostic criteria, and the calculated HScore was 209, indicating a high probability of secondary HLH. Initial empirical therapy with intravenous cefoperazone-sulbactam and doxycycline failed to achieve clinical improvement. Following bronchoalveolar lavage culture results, antibiotics were escalated to meropenem and tigecycline, resulting in rapid clinical and hematological recovery without immunosuppressive therapy. This case is unique as recovery was achieved solely with appropriate antimicrobial therapy despite fulfilling diagnostic criteria for HLH. It highlights the importance of early recognition of infection-triggered HLH and emphasizes that prompt treatment of the underlying trigger may prevent unnecessary immunosuppression in selected patients.